Visualizing Retinal Pigment Epithelium Phenotypes in the Transition to Geographic Atrophy in Age-Related Macular Degeneration

Abstract

Purpose To inform the interpretation of clinical optical coherence tomography and fundus autofluorescence?imaging in geographic atrophy (GA) of age-related macular degeneration (AMD) by determining the distribution of retinal pigment epithelium (RPE) phenotypes in the transition from health to atrophy (GA) in donor eyes. Method In RPE-Bruch’s membrane flat mounts of 2 GA eyes the terminations of organized RPE cytoskeleton and autofluorescent material were compared. In high-resolution histological sections of 13 GA eyes, RPE phenotypes were assessed at ±500 and ±100 µm from the descent of the external limiting membrane (ELM) towards Bruch’s membrane. The ELM descent was defined as curved, reflected, or oblique in shape. Thicknesses of RPE, basal laminar deposit (BLamD), and RPE+BLamD were measured. Results A border of atrophy that can be precisely delimited is the ELM descent, as opposed to the termination of the RPE layer itself, because of dissociated RPE in the atrophic area. Approaching the ELM descent, the percentage of abnormal RPE morphologies increases, the percentage of age-normal cells decreases, overall RPE thickens, and BLamD does not thin. The combination of RPE plus BLamD is 19.7% thicker at −100 µm from the ELM descent than at −500 µm (23.1 ± 10.7 vs 19.3 ± 8.2 µm; p=0.05). Conclusion The distribution of RPE phenotypes at the GA transition support the idea that these morphologies represent defined stages of a degeneration sequence. The idea RPE dysmorphia including rounding and stacking helps explain variable autofluorescence patterns in GA 14 is reinforced. The ELM descent and RPE+BLamD thickness profile may have utility as SDOCT metrics in clinical trials.

High-Resolution Adaptive Optics Transscleral Flood Illumination Imaging Allows Phenotyping of Age-Related Macular Degeneration

“…Progressive RPE dysfunction and degeneration have been implicated in both dry and neovascular AMD, driven by a combination of oxidative stress, inflammation, and lipid accumulation [ 25 , 26 , 27 , 28 , 29 ]. Our study confirms that areas corresponding to atrophy or pre-atrophy lack the typical hexagonal RPE mosaic seen in healthy retinas—a finding consistent with prior AO-TFI and AO-SLO studies [ 2 , 13 ]. The reflectance profiles of the patterns we observed further suggest structural alterations at the subcellular level, possibly involving RPE thinning, disruption, or dropout.…”

High-Resolution Adaptive Optics Transscleral Flood Illumination Imaging Allows Phenotyping of Age-Related Macular Degeneration

“…Progressive RPE dysfunction and degeneration have been implicated in both dry and neovascular AMD, driven by a combination of oxidative stress, inflammation, and lipid accumulation [ 25 , 26 , 27 , 28 , 29 ]. Our study confirms that areas corresponding to atrophy or pre-atrophy lack the typical hexagonal RPE mosaic seen in healthy retinas—a finding consistent with prior AO-TFI and AO-SLO studies [ 2 , 13 ]. The reflectance profiles of the patterns we observed further suggest structural alterations at the subcellular level, possibly involving RPE thinning, disruption, or dropout.…”

Fluorescence Lifetime Patterns of Retinal Pigment Epithelium Atrophy in Patients with Stargardt Disease and Age-Related Macular Degeneration

“…Similar findings were observed in previous studies [16,18]. The heterogeneity within areas of RPE atrophy might, on the one hand, be explained by varying degrees of photoreceptor degeneration, resulting in residual amounts of visual cycle byproducts [29,30]. On the other hand, short lifetimes within atrophic lesions were mainly seen within the central macular area.…”

Modeling inducible neuropathologies of the retina with differential phenotypes in organoids

“…Ultrastructural images show not only that the most apical ordered structure of the OLM is lost in pathologic regions (Figures 5C3-C5, D3, D4), but also that the contiguous region below the OLM is affected: The apical cell layer is mostly formed by cell contacts between amorphous cells larger than in controls (Figures 5A1-A4, D1-D4), some of which infrequently show a pathologic perpendicular orientation. These data support the hypothesis that lost PRs become replaced by MG, some MG overgrow remaining PR cells or replace lost ones (Figure 5D3, blue pseudocolored cell), as reported in animal models and patients (Guidry et al, 2002;Sullivan et al, 2003;Wu et al, 2003;Lewis et al, 2010;Jones et al, 2016b;Zanzottera et al, 2016;Edwards et al, 2017;Li et al, 2018Li et al, , 2021, which might be part of a process forming glial seal-like scars. Notably, some cells are localized ectopic of the OLM (Figures 5A4, D3), suggesting that PRs might degenerate via cell extrusion as we previously also observed in HT-HROs (Volkner et al, 2022).…”

High-Resolution Adaptive Optics Transscleral Flood Illumination Imaging Allows Phenotyping of Age-Related Macular Degeneration

“…Progressive RPE dysfunction and degeneration have been implicated in both dry and neovascular AMD, driven by a combination of oxidative stress, inflammation, and lipid accumulation [ 25 , 26 , 27 , 28 , 29 ]. Our study confirms that areas corresponding to atrophy or pre-atrophy lack the typical hexagonal RPE mosaic seen in healthy retinas—a finding consistent with prior AO-TFI and AO-SLO studies [ 2 , 13 ]. The reflectance profiles of the patterns we observed further suggest structural alterations at the subcellular level, possibly involving RPE thinning, disruption, or dropout.…”

Fluorescence Lifetime Patterns of Retinal Pigment Epithelium Atrophy in Patients with Stargardt Disease and Age-Related Macular Degeneration

“…Similar findings were observed in previous studies [16,18]. The heterogeneity within areas of RPE atrophy might, on the one hand, be explained by varying degrees of photoreceptor degeneration, resulting in residual amounts of visual cycle byproducts [29,30]. On the other hand, short lifetimes within atrophic lesions were mainly seen within the central macular area.…”

Modeling inducible neuropathologies of the retina with differential phenotypes in organoids

“…Ultrastructural images show not only that the most apical ordered structure of the OLM is lost in pathologic regions (Figures 5C3-C5, D3, D4), but also that the contiguous region below the OLM is affected: The apical cell layer is mostly formed by cell contacts between amorphous cells larger than in controls (Figures 5A1-A4, D1-D4), some of which infrequently show a pathologic perpendicular orientation. These data support the hypothesis that lost PRs become replaced by MG, some MG overgrow remaining PR cells or replace lost ones (Figure 5D3, blue pseudocolored cell), as reported in animal models and patients (Guidry et al, 2002;Sullivan et al, 2003;Wu et al, 2003;Lewis et al, 2010;Jones et al, 2016b;Zanzottera et al, 2016;Edwards et al, 2017;Li et al, 2018Li et al, , 2021, which might be part of a process forming glial seal-like scars. Notably, some cells are localized ectopic of the OLM (Figures 5A4, D3), suggesting that PRs might degenerate via cell extrusion as we previously also observed in HT-HROs (Volkner et al, 2022).…”

High-Resolution Adaptive Optics Transscleral Flood Illumination Imaging Allows Phenotyping of Age-Related Macular Degeneration

“…Progressive RPE dysfunction and degeneration have been implicated in both dry and neovascular AMD, driven by a combination of oxidative stress, inflammation, and lipid accumulation [ 25 , 26 , 27 , 28 , 29 ]. Our study confirms that areas corresponding to atrophy or pre-atrophy lack the typical hexagonal RPE mosaic seen in healthy retinas—a finding consistent with prior AO-TFI and AO-SLO studies [ 2 , 13 ]. The reflectance profiles of the patterns we observed further suggest structural alterations at the subcellular level, possibly involving RPE thinning, disruption, or dropout.…”

Fluorescence Lifetime Patterns of Retinal Pigment Epithelium Atrophy in Patients with Stargardt Disease and Age-Related Macular Degeneration

“…Similar findings were observed in previous studies [16,18]. The heterogeneity within areas of RPE atrophy might, on the one hand, be explained by varying degrees of photoreceptor degeneration, resulting in residual amounts of visual cycle byproducts [29,30]. On the other hand, short lifetimes within atrophic lesions were mainly seen within the central macular area.…”

Modeling inducible neuropathologies of the retina with differential phenotypes in organoids

“…Ultrastructural images show not only that the most apical ordered structure of the OLM is lost in pathologic regions (Figures 5C3-C5, D3, D4), but also that the contiguous region below the OLM is affected: The apical cell layer is mostly formed by cell contacts between amorphous cells larger than in controls (Figures 5A1-A4, D1-D4), some of which infrequently show a pathologic perpendicular orientation. These data support the hypothesis that lost PRs become replaced by MG, some MG overgrow remaining PR cells or replace lost ones (Figure 5D3, blue pseudocolored cell), as reported in animal models and patients (Guidry et al, 2002;Sullivan et al, 2003;Wu et al, 2003;Lewis et al, 2010;Jones et al, 2016b;Zanzottera et al, 2016;Edwards et al, 2017;Li et al, 2018Li et al, , 2021, which might be part of a process forming glial seal-like scars. Notably, some cells are localized ectopic of the OLM (Figures 5A4, D3), suggesting that PRs might degenerate via cell extrusion as we previously also observed in HT-HROs (Volkner et al, 2022).…”